Tidalforce S-750 Build by Preston

[pvorlicek]

Just finished the build of my first S-750 frame. This first one is for my wife who does not like high speed or high power … so there is nothing impressive on that front. Here are the important specs:

Frame: Tidalforce S-750 with accessories (from JD)
Motor: BMC V1 built onto an Alex DX32 rim (By JohnRobHolmes) with BMC 20A controller
Front wheel: Rhyno Lite
Tires: Maxxis Hookworms
Battery: Headway 12S pack from EVComponents (BMS removed)
Front fork: Rockshox Judy (Ebay – Used)
Cycle Analyst: YES!!! (Stand Alone)

I’ve taken in for 5 break-in rides so far and the bike is coming together. The bike goes 20MPH on the flat with no pedaling. This is my 1st geared hub motor and I like it … and this will be my standard for my next build (but at higher power … probably the BMC V3 from Ilia). The thing I like best is not pedaling against the EMF of the motor. Makes a little more noise but not a bother to me at all.

One work for the ride on this bike: SWEET. It rides very smoothly thanks to the hookworms and the sold frame. The hookworms corner phenomenally. These tires are fat and round so when the bike is leaned it feels no different than the flats.

This was my first bike build ever (I didn’t even know what a headset was before I started). Issues in the build:

1) This being my first bike build, it was painfully slow. I spent a lot of time on the Internet researching and buying. The biggest pain was getting the spacers and washers right for the rear wheel (had to buy the C-Washer from Justin and ebikes.ca) and getting the brakes to work on these HUMONGOUS REAR RIM AND TIRE. I started out with the V Brakes for the rear, then changed to disc (couldn’t get to fit and then back to V brakes … which is where I am now.
2) I also had a small problem with the lacing of the rear wheel. It was not dished properly so I had to dish it a little to keep the tire from rubbing against the rim. There is about ¼â€ between the rim and the tire on this beast.
3) Battery: like others have noted, I have had some issues with this pack. As I mentioned, I removed the BMS immediately. Based on my previous BMS problems, I decided to run unprotected but took the following precautions:
a) I wired in some connectors so that I could use a Cellog8 (see photo) to quickly monitor individual cell voltages.
b) I am using a Cycle Analyst (CA) to monitor the pack voltage. I have “calibrated” the CA to know that if my pack goes below 36V under a 2C load, I need to watch out. Normal voltage on my pack (from the CA) is about 39.5 under no load (after I have burned off .2 or .3 AH), 37.5 under 1C and 36.5 under 2C. Anything “significantly” below this is cause for concern. I learned this strategy from my 48V Headway pack (16S). My recommendation: know your pack.
c) Maximum discharge is 2C and so far, I have not gone more than 6AH on the pack (according to my CA). So, I have not stressed this pack.
d) I spent 2 weeks “playing” with the pack (off the bike, on the bench/kitchen table): charging/discharging … so I am beginning to know this pack pretty well. I have a couple of cells that I suspect may be weak … but the jury is still out. I will put a separate post about what I have learned about the battery pack.

Here is the approximate damage:

1) Bike frame and parts from JD: $175
2) Additional parts: $150
3) Motor/controller/throttle: $325 (Ebay)
4) Rear wheel build with tire: $150
5) Front wheel with tire and disc brakes: $150
6) Battery: $275
7) Charger/Cycle Analyst/Charger: in stock

So, I think I am just north of $1,200 for this setup … $1,500 if you include all the stuff I had “in stock”. All prices include shipping, taxes, etc.

Good decisions:

Upgraded kick stand
Geared hub motor
Maxxis Hookworms
Cycle Analyst (an absolute MUST)

Bad decisions:

Purchased a few extra parts from JD that I didn’t need (cartridge, front V brakes).
I’m sure there are some others … but I won’t know them for another 3 to 6 months.

Right now I am quite happy. The wife has taken it for a couple of rides and likes it as well … but has NO IDEA when the CA says or does.

I’m not 100% finished as I need to clean up the cables in the back.

[pvorlicek]

more photos

[oatnet]

Nice Build! I really like the choices you have made. Hookworms really help achieve great lean angles, don't they? If you are already planning your next build, you are officially addicted... Let me know when you want more frames .

-JD

[pvorlicek]

Nice Build! I really like the choices you have made. Hookworms really help achieve great lean angles, don't they? If you are already planning your next build, you are officially addicted... Let me know when you want more frames .

-JD

If you recall, I purchased 2 frames from you ... the 2nd one is for me. I'm thinking about the BMC V3 from Ilia. Don't worry ... I am already addicted. I have 5 ebikes (6th on the way) for 2 people. Is that the definition of an addiction?

[mikeross]

Hey, pvorlicek: I like your build a lot! These Tidal Force frames are a great start to a very nice ebike. You made some wise decisions regarding motor/controller/rear rim build. I am seriously thinking of rebuilding my 9C stock rear wheel - with all the weight on the rear (from me, battery, motor, and whatever else is being carried) a good, sturdy rear wheel is a must. Mine makes a bit of a creaking noise while underway, which can't be good. Keep me advised on what you learn about your Headway pack. I tried to be real careful with mine - replaced the stock BMS with a Ping Signalab BMS, shallow discharge, easy riding, but it went to heck on me anyway. I have a hole in my battery case with the balance wire plug coming out, too (after removing the Signalab BMS).

Very nice work!! um, you have 5, going on 6, of these things??!!

Mike

[pvorlicek]

Mike:

Call me Preston please. I followed your thread so I know the pain you have been feeling. I have 3 Headway packs and have "killed" 5 cells (out of 48 that are working). At this point I might have 1 spare. Three I "killed" from my negligence ... and I think two of the cells were runts form the factory. Part of the reason I went with the BMC was weight ... very light so overall I think my rear is less than a 36V (10AH) SLA battery alone.

2 of my other ebikes are basically junk ... I'll probably give them to some neighborhood kids to play with or maybe the local high school. This bike was my first "real" quality build.

I see that you do not have a Cycle Analyst. In my opinion, this is a requirement, not an option. You can see the voltage as you are cycling and the amp-hours that you have burned. I've gotten to the point where I can quickly tell if there is an issue with my pack ... I know where my pack voltage should be ... and if it is more than 0.5 to 1 volt off ... I know it's time to investigate. On the good news side, I have a 48V (16S) pack that I have run for 250 cycles with never a need to single cell charge.

The Cellog 8 is also a big help for quickly measuring individual cell voltage.

I will add a post to my thread about my battery issues tomorrow.

BTW: I commute with my bike every day.

[oatnet]

If you recall, I purchased 2 frames from you ... the 2nd one is for me. I'm thinking about the BMC V3 from Ilia. Don't worry ... I am already addicted. I have 5 ebikes (6th on the way) for 2 people. Is that the definition of an addiction?

I know you bought (2) frames - my joke was that due to the addiction I was implying, you would burn through that and be jonesing for #3/#4 next week. At least that is how it works for me

-JD

[ambroseliao]

Preston,

Very nice clean build. I like the look of the double tiered rack as well.

Ambrose

[pvorlicek]

Preston,

Very nice clean build. I like the look of the double tiered rack as well.

Ambrose

Except for the cables that still need to be tidied up!

Thanks,

Preston

[El_Steak]

Nice clean build Preston, gives me some ideas for my second TF frame

[pvorlicek]

My pack is the Headway 12S pack that was sold by EVComponents prior to extinction. I knew the BMS included was bad and didn't care because I have given up on the current generation of BMS's after a bad experience with the Headway BMS ... and the fact that I have a 16S pack that is working perfectly without a BMS.

So, I opened the pack, pulled out the BMS and put a fuse in-line with the discharge path. I also drilled a hole in the side of the battery case and installed 2 connectors to allow me to quickly monitor the cell voltage (Cellog and also try to balance charge the cells with the iMax charger/discharger (http://hobbyking.com/hobbyking/store/uh ... _1-8_Cells) if necessary.

I started a bulk charge of the pack (Soneil SLA charger) and a couple of cells peaked up to 4+ volts so I suspected some cells out of balance (different levels of charge state). Unfortunately, my single cell (Tenergy) charger failed on me so I started to charge and discharge the pack using the iMax to see if cycling the pack would bring it into balance. On the discharge cycle I was seeing some cells drop before others confirming my suspicion of an unbalanced pack. I have a two cell charger and a spare cell that I used to “juice up” the cells that I felt were under charged. This was not a clean process and I was only doing it in desperation because I did not have a working single cell charger. After I did this I did 4 or 5 more charge/discharge cycles and the pack steadily began to improve (meaning I was able to take more AH out of the pack before cell voltage dropped below 2.5V).

THIS TOOK A LONG TIME (more than 12 hours per cycle) and I was anxious to do some biking!

After I got to the point where I was able to take out 7AH before hitting my 2.5V threshold, I decided to put the pack on my bike … where it is now.

I have been monitoring my pack with the Cellog8 at the end of each ride and during the bulk charge. Cells are still out of balance … but I hope they are getting closer. As of today, I have 8 rides/cycles … nothing more than 4.5 AH. I will do a 6 to 7 AH discharge this evening and see what I get. I’m hoping that I will see the pack voltage (no load) above 39.0 Volts and not below 35 Volts under a 2C load after taking out 7 AH from the battery. If not, the battle continues ….

[The Journey Guy]

Beautiful build, Preston! Stunning, in fact.

Where did you get the rear rack? Would it be possible for someone to purchase only that rack, or does it come with the frame you bought?

TJG

[oatnet]

Beautiful build, Preston! Stunning, in fact.

Where did you get the rear rack? Would it be possible for someone to purchase only that rack, or does it come with the frame you bought?

TJG

That rear rack comes with the headway pack, not with my frames.

-JD

[The Journey Guy]

Hey JD. So, that effectively means that I cannot obtain a rack like that, due to the internal turmoil at EVC?

Disappointing...

TJG

[oatnet]

Hey JD. So, that effectively means that I cannot obtain a rack like that, due to the internal turmoil at EVC?

Disappointing...

TJG

That is the only place I've seen that specific version - I think I just saw something similar in the ebike-kit.com thread for their amazing $200 geared motor kit deal though, if you follow theIr link to the deal on their website.

-JD

[ambroseliao]

This one at e-bikekit.com sure looks like the same double tiered battery rack that EVComponents used to sell. Price seems reasonable too at $32 without shipping.

http://www.e-bikekit.com/shop/index.php ... 8&parent=2

Ambrose
(no connection with e-bikekit.com except as a satisfied customer)

[The Journey Guy]

Hi Ambrose. I ordered one of those racks when they first became available, about a month or so ago. Unfortunately, they are not the same rack. The rack in the photos that are at the first of this thread are much stronger. The material they are made of is more flattened, which makes the sides of the rack more flat, making it easier to mount a large flat object like a battery box, etc.

Maybe I'll need to put a thread in the Wanted section for one of the EVC rear racks. I might get a lead or two that way.

TJG